Concave describes shapes that curve inward, like an hourglass. Convex describes shapes that curve outward, like a football (or a rugby ball).

A curved mirror is a mirror with a curved reflecting surface. The surface may be either convex (bulging outward) or concave (recessed inward). Most curved mirrors have surfaces that are shaped like part of a sphere, but other shapes are sometimes used in optical devices.

Concave mirrors are used as searchlights, shaving mirrors, satellite dishes, and many more. These mirrors have the property to collimate and concentrate light rays. Concave mirrors in torches and headlights are used as reflectors.

A concave mirror is also known as a “Converging Mirror” since in these type of mirrors light rays converge at a point after they strike and are reflected back from the reflecting surface of the concave mirror.

Concave Synonyms – WordHippo Thesaurus….What is another word for concave?

depressed	hollow
cupped	dented
dished	excavated
hollowed	incurvate
scooped	biconcave

A concave lens is a lens that possesses at least one surface that curves inwards. It is a diverging lens, meaning that it spreads out light rays that have been refracted through it. A concave lens is thinner at its centre than at its edges, and is used to correct short-sightedness (myopia).

Reflection from a Concave Mirror As the object moves towards the mirror the image location moves further away from the mirror and the image size grows (but the image is still inverted). As the object moves towards the mirror inside the focal point the image becomes virtual and upright behind the mirror.

The magnification equation is m=−dido. For concave mirrors, when the object is outside C, the image will be between C and F and the image will be inverted and diminished (smaller than the object). For concave mirrors, when the object is between C and F, the image will be beyond C and will be enlarged and inverted.

Some of the most important and common applications of the concave mirror are described below.

• Used in shaving mirrors.
• Concave mirror uses in the ophthalmoscope.
• Uses of concave mirror in astronomical telescopes.
• Concave mirrors used in headlights.
• Used in solar furnaces.

In a concave mirror, when the distance of the object is less than the focal length, the magnification will be greater than one. When the distance of the object is greater than the focal length, then the magnification is less than one.

In a concave mirror, the magnification is the ratio of the height of the image to the height of the object. The magnification is also equal to the negative of the ratio of the distance of the image from the mirror to the distance of the object from the mirror .

A concave mirror gives the dentist a magnified reflection of the mouth while also refracting a bit of light. This means the image in the mirror is larger, brighter, and, for the dentist, easier to see.

Answer: the focal length, is positive for a concave mirror, and negative for a convex mirror. When the image distance is positive, the image is on the same side of the mirror as the object, and it is real and inverted.

Any distances measured on that side are positive. Distances measured on the other side are negative. f, the focal length, is positive for a concave mirror, and negative for a convex mirror. When the image distance is positive, the image is on the same side of the mirror as the object, and it is real and inverted.

Focal length is positive for a concave mirror and negative for convex mirror. So, the correct answer is “Option A”. Note: We know that images formed by the concave mirror may be inverted or erect, real image or virtual image and it can be smaller, larger or of the same size depending on the situation of the object.

Since, object is always placed in front of the mirror hence the sign of object is taken as negative. Since, the centre of curvature and focus lie in front of the concave mirror, so signs of radius of curvature and focal length are taken as negative in the case of concave mirror.

Suppose an object is placed u cm in front of a spherical mirror of focal length f such that the image is formed v cm from the mirror, then u, v and f are related by the equation; 1/f= 1/u + 1/v. This equation is referred to as the mirror formula. The formula holds for both concave and convex mirrors.

Concave mirrors can produce both real and virtual images; they can be upright (if virtual) or inverted (if real); they can be behind the mirror (if virtual) or in front of the mirror (if real); they can also be enlarged, reduced, or the same size as object.

Image formed by a convex mirror is always virtual and erect. When an object is placed at infinity, virtual image is formed at focus and the size of the image is smaller.

Convex mirrors are widely used as rear-view mirrors in automobiles and vehicles because it can diverge light beams and make virtual images.

Uses of Convex Mirrors

• Inside buildings. You might have noticed that large office buildings, stores, hospitals, and other many other buildings have convex mirrors in the corners.
• Sunglasses. We might have used sunglasses many times.
• Vehicle mirrors.
• Magnifying glasses.
• For security purposes.
• Street light reflectors.

convex mirror

Convex mirrors

Convex mirror are used as reflector in street lamps whereas concave mirror is used as a reflector in torch and car headlight.

Convex mirror is used in street light because it has the property of divergence . Therefore light rays coming from bulb diverges in convex mirror and cover a large distance . In case of a concave mirror ,it has property of convergence .

Parabolic Concave mirrors

Concave mirrors